This invention relates generally to shaft sealing devices for use of rotating equipment. Proper maintenance of rotating equipment is difficult to obtain because of the extreme equipment duty cycles, the lessening service factors, the design of the equipment and the lack of spare rotating equipment in may processing plants.
Various form of shaft sealing devices have been utilized to attempt to protect the integrity of the bearing environment, including rubber lip seals, clearance labyrinth seals and attraction magnetic seals. Lip seals or O-ring shaft seals can quickly wear out and fail. These seals are also known to permit excessive amounts of moisture and other contaminants into the oil reservoir of the operating equipment, precipitating failure.
Labyrinth-type seals involve closely related stator and rotor rings, which do not contact each other, but define labyrinth passages between them, having been devised and utilized and are illustrated in Orlowski, U.S. Pat. Nos. 4,706,968; 4,989,883; 5,069,461 and the additional patents to Orlowski cited therein. As described in Orlowski U.S. Pat. Nos. 4,989,883 and 5,069,461, improvements in labyrinth seals are disclosed and claimed including the utilization of various forms of O-ring seals to improve the static sealing action when the shaft is at rest, and non-contact dynamic sealing action is provided when the shaft is rotating.
In addition, an improvement in the case of oil mist lubrication, a coalescing ring is disclosed and claimed in Orlowski U.S. Patent application Ser. No. 08/882,123. This coalescing ring was located so as to contract a second rotor with an angle on its profile in a vertical plane away from the shaft. A coalescing ring adjacent to the shaft was disclosed by Orlowski's U.S. Patent application Ser. No. 08/701,815. This second rotor has an ever-increasing diameter and tends to impel the coalesced lubricating oil back toward the equipment where it can be controlled.
In many situations and applications the rotating shafts are partially flooded with lubricant prior to or while running.
Such is the case with nearly all gearboxes, where a pool of lubricant must be present to ensure that the bearings are not rotated without an adequate supply of lubricant covering their lower components. Oil mist lubrication as described in the references also poses as another unique problem. The mist that does not impinge on the bearing surfaces or is not coalesced, it is able to enter the environment outside the bearing enclosure. Sometimes notched lip seals provide an escape route and sometimes the spent mist is directed through pipes that convey the mist to recovery, or in some instances, the mist may be coalesced and returned to the pump. This present invention is designed and functions to prevent the escape of oil or lubricant in these difficult lubrication situations i.e., the flooded or partially flooded oil mist lubrication systems.
An object of the present invention is to provide a seal around a rotating shaft, and between the shaft and the housing, to prevent leakage of lubricant from the housing, and also prevent the entry of contaminants into the housing by the use of a lubricous insert in the stator, which combined with a elongation of the rotor provides total and absolute sealing i.e., prevents leaking of the lubricant outside the housing and simultaneously prevents the entrance of the contaminants into the bearing.
Prior art sealing mechanisms utilizing labyrinth seals have provided adequate sealing in many of the normal positions and levels of lubricants. This invention provides a novel seal, which provides no forced lubricant in or out of the bearing housing and likewise contaminants. Prior art seals force lubricant and contaminants either in or out of the housing, depending on the direction of rotation of the spiral tool marks on the hard surface of the rotor. In addition, because the normal bearing sealing surface is softer than the rotating portion or rotor of the seal, grooves must be reformed after axial movement of the shaft. This invention removes the spiral groove normally formed on the rotor-sleeve, which tends to constantly and continually abrade the seal to sleeve interface when the shaft is running.
This invention provides an insert into the stator, which forms a sealing surface, which will rotate against a portion of a rotor rather than against the shaft. This lack of contact with the shaft prevents damage to the shaft from the wear and tear of the sealing material. Another advantage to utilizing the seal insert into the stator is that it provides a means for changing out of the installation of the sealing material either at the manufacturer or into existing machinery in the field.
Another advantage of this invention is the novel machining of the surface of the rotor, sleeve or axial elongation of the rotor, which provides finely or precisely contoured parallel circular asperities or disk like profiles on the rotor sleeve surface that either lead into or out of the bearing housing. This novel machining provides a plurality of parallel disks with a plurality of circular grooves between the disks, although microscopic in size, are all essentially the same size, shape and have equal spacing so that any axial movement of the shaft and or the rotor will reposition the shaft or rotor interface over a new set of identical grooves.
Grinding of the surface of the rotor sleeve will produce an extremely smooth and amorphous finish, but will produce hydroplaning of the sealing components which will permit the movement of the oil out of and away from the bearing.
Thus this novel bearing isolator operates to provide a rotor that encompasses a larger portion of the shaft and also protects the shaft. Total restriction or sealing of the housing and the lubricant therein to the exterior is attained. This bearing isolator has been tested in the laboratory and has run over a thousand hours without a single drop of lubricant leaking to the exterior.
This invention also requires accomplishing improved sealing providing a unique energizing ring positioned in the sealing material that have been inserted into the stator. This ring maintains a constant pressure between the inserted sealing material and the rotor.
Other object advantages and embodiments of the invention will become apparent upon reading the following detailed description upon reference to the drawings and the prior art patents.
This invention provides total sealing regardless of the direction of the rotation of the shaft as contrasted to the prior art to which is due to the manner of machining of spiral grooves in the surface of the rotor. This machined grooves act as a screw to drive the lubricant either in or out of the housing, depending upon the direction of rotation verses the direction of the screw surface which has been machined into the rotor.